1. Field of the Invention
The present invention relates to a magnetic head suspension for supporting a magnetic head slider that reads and/or writes data from and to a recording medium such as a hard disk drive, and also relates to a manufacturing method thereof.
2. Related Art
A magnetic head suspension that supports a magnetic head slider is required to have the magnetic head slider rapidly and accurately moved to a center of a target track.
More specifically, the magnetic head suspension has a proximal side that is directly or indirectly connected to an actuator such as a voice coil motor and a distal side that supports the magnetic head slider, and is swung around a swing center by the actuator so as to move the magnetic head slider along a seek direction parallel to a disk surface until the center of the target track.
In order to have the magnetic head slider rapidly and accurately moved to the target track, the magnetic head suspension has to be configured so as to be capable of reducing a vibration of the magnetic head slider as much as possible even in a case that a frequency of a drive signal that drives the actuator is raised.
By the way, vibrations in various modes are generated in the magnetic head suspension when it is swung by the actuator. The vibrations deteriorate a positioning accuracy of the magnetic head slider with respect to the target track.
Out of the various vibration modes possibly generated in the magnetic head suspension, the first torsion mode, the second torsion, the third torsion mode and the sway mode (oscillation mode) have resonance frequencies within a relatively low frequency range. It is therefore required to prevent or reduce a displacement of the magnetic head slider due to the vibrations of these vibration modes.
Displacement amounts (gains) of the magnetic head slider from the target track due to the vibrations in the first to third torsion modes can be minimized by adjusting a bending angle at a bending portion, which is provided at an intermediate region of a load beam part, and/or adjusting a position of the bending portion at the load beam part in a suspension lengthwise direction, and also adjusting a position of a bending portion, which is provided at a load bending part of the magnetic head suspension, in the suspension lengthwise direction.
That is, an adjustment of the bending angle at the bending portion at the load beam part and/or an adjustment of the position thereof in the suspension lengthwise direction to respective optimum values as well as an adjustment of the position of the bending portion at the load bending part in the suspension lengthwise direction to an optimum value make it possible to minimize the displacement amount of the magnetic head slider from the target track due to the vibrations in the first to third torsion modes even if the vibration in any of the first to third modes is generated in the magnetic head suspension.
For example, Japanese Unexamined Patent Publication No. 11-007740 discloses a magnetic head suspension including a load bending part with two bending portions at which bending angles are same as each other in order to reduce a gain of the magnetic head slider at the time when a resonant vibration is generated in the suspension.
On the other hand, a displacement amount (gain) of the magnetic head slider from the target track due to the vibration in the sway mode cannot be minimized by adjusting the bending angle at the bending portion at the load beam part and/or adjusting the position thereof in the suspension lengthwise direction, and also adjusting the position of the bending portion at the load bending part in the suspension lengthwise direction.
Accordingly, in order to prevent or reduce the displacement of the magnetic head slider from the target track due to the vibration in the sway mode, it is needed that the vibration in the sway mode is not likely to be generated in the magnetic head suspension. That is, it is needed to raise a resonant frequency of the magnetic head suspension in the sway mode as much as possible so as to prevent the resonant vibration in the sway mode from being generated therein as much as possible even if the frequency of the drive signal is raised in order to rapidly move the magnetic head slider to the target track.
As a typical method for raising the resonant frequency in the sway mode, it is conceivable to widen a proximal side of the load beam part so as to enhance rigidity of the magnetic head suspension with respect to a suspension width direction.
However, the magnetic head suspension needs the load bending part that has low rigidity so as to generate a load for pressing the magnetic head slider toward the disk surface. Accordingly, even if the load beam part is configured so as to have high rigidity with respect to the suspension width direction, rigidity of the magnetic head suspension as a whole with respect to the suspension width direction cannot be raised so much.